高校地质学报2018，Vol.24Issue(2)：160-171,12.DOI:10.16108/j.issn1006-7493.2017093
内蒙古大青山地区同盛茂晚石炭世火山岩的年代学、地球化学和Hf同位素研究及其地质意义
Geochronology,Geochemistry,and Hf isotopic Compositions of the Late-Carboniferous Volcanic Rocks in Tongshengmao of Daqinshan Area,Inner Mongolia and Their Geological Implications
摘要
Abstract
The northern margin of North China Block(NCB)is a key region for exploring the closure and evolution of the Paleo-Asian Ocean, which has attracted much attention. Previous research has shown that there exists intensive late-Paleozoic magmatism which is composed almost entirely of intrusives and lack of coeval volcanic rocks. In this paper, we present detailed LA-ICP-MS zircon U-Pb ages,major and trace elements,and Hf isotopic compositions of the volcanic rocks from the upper part of the Shuanmazhuang Formation, Tongshengmao of Daqinshan district in Inner Mongolia. LA-ICP-MS zircon U-Pb dating shows that the volcanic rocks of the upper part of the Shuanmazhuang Formation were generated at 305 Ma. The volcanic rocks consist of weakly-welded rhyolitic tuffs that suffered from intense kaolinization.These volcanic rocks have low REE contents with subtle negative Eu anomalies and show low HREE (e.g., Y, Yb) contents. They also have negative εHf(t) values ranging from-8.3 to-4.0. These characteristics suggest that they were likely generated from partial melting of the thickened NCB crustal basements, and with some involvement of mantle-derived magmas.In combination with the latest reports about the distribution of late Paleozoic volcanic rocks in the northern margin of NCB,it is inferred that there likely existed two stages of volcanism at least during the late-Paleozoic,with ages of 305～290 Ma and 278～261 Ma,and a peak volcanism at 272 Ma.关键词
华北北缘/晚石炭世/火山岩/锆石U-Pb年龄/锆石Hf同位素Key words
the northern margin of NCB/Late-Carboniferous/volcanic rocks/zircon U-Pb age/zircon Hf isotopic compositions分类
天文与地球科学引用本文复制引用
张乔,李玉宏,陈高潮,韩伟,王靖..内蒙古大青山地区同盛茂晚石炭世火山岩的年代学、地球化学和Hf同位素研究及其地质意义[J].高校地质学报,2018,24(2):160-171,12.基金项目
国家自然科学基金项目(41572131 （）
41202104)资助 （）
